Combine the broth and water in a large saucepan and bring to a boil over high heat. Once boiling, cover the pot and reduce the heat to medium-low to maintain a bare simmer while you prepare the rice.

Melt half the butter in a Dutch oven over medium heat. Add the onion and salt and cook until the onion is softened and translucent, 4 to 5 minutes. Stir in the garlic and cook until fragrant.

Add the rice to the Dutch oven and cook, stirring often, until the edges of the grains begin to turn translucent, about 3 minutes.

Pour in the wine and cook, stirring constantly, until it is fully absorbed. Stir in 5 cups of the hot broth mixture, then reduce the heat to medium-low. Cover and simmer until almost all the liquid has been absorbed and the rice is just al dente, 18 to 19 minutes, stirring only twice during the process.

Add 3/4 cup of the hot broth mixture and stir gently and constantly until the risotto becomes creamy and thick, about 3 minutes. Stir in the Parmesan, then remove the pot from the heat. Cover and let the rice rest for 5 minutes—this allows the starches to settle for a better texture.

Stir in the remaining butter and the lemon juice. Season with salt and pepper to taste. If the risotto looks too stiff, stir in the remaining broth mixture as needed to loosen the consistency until it flows slightly on the plate. Serve immediately.